The present invention relates to a silylating agent suitable for the protection of active hydrogen during the execution of organic reactions.
Based on its commercial availability and cost, trimethylchlorosilane was a good earlier silylating agent for the protection of active hydrogen (for example, the hydroxyl group or amine NH) during the synthesis of pharmaceuticals, intermediates for chemical production, and so forth. However, silylation of the hydroxyl group or amine NH by the trimethylsilyl group did not always give satisfactory results because of this group's performance as a protective group during organic reactions, i. e., the chemical stability of the silylation product was inadequate. Due to this, t-butyldimethylchlorosilane became the leading silylating agent because it generates a protective group which is satisfactorily stable during the execution of organic reactions. Still, the t-butyldimethylsilyl group is in fact too stable, and fairly vigorous reaction conditions are required for the regeneration of active hydrogen in the desilylation reaction following execution of the necessary organic reaction(s). This also results in such problems as destruction of other functional groups.
The present invention seeks to solve the problems arising in the above-described prior art through the introduction of a silylating agent which will yield a very chemically stable silylation product, but which will also react more easily in the desilylation reaction than the t-butyldimethylsilyl group.